The present invention relates to a new and improved construction of a spinning device for open-end spinning.
In its more particular aspects, the present invention specifically relates to a spinning device for open-end spinning and which spinning device contains a spinning rotor which is rotatable about a predetermined rotational axis, and a withdrawal arrangement for withdrawing the spun yarn or the like obtained by the open-end spinning operation.
In a spinning device for open-end spinning such as known, for example, from German patent No. 3,220,402 there is provided a withdrawal nozzle of the currently common construction which is combined with a balloon guide. The thread or yarn to be withdrawn forms a balloon in the balloon guide and the diameter of this balloon is subjected to multiple variations during each revolution thereof. Elements interfering with the balloon are provided and the thread impacts against such elements in order to induce thread or yarn formation. However, this is disadvantageous for the thread or yarn which is unduly stressed due to the plucking actions exerted upon the thread or yarn during this operation.
A withdrawal funnel as known, for example, from Czechoslovakian patent No. 129,036, granted Sept. 15, 1968, contains a projection which extends along a spiral-shaped path in a conical portion of the withdrawal funnel and along a helical path in a tubular portion of the withdrawal funnel. In such arrangement the projection exerts practically no effect upon the thread or yarn in the tubular portion and the overall effect is inadequate.
A spinning device for open-end spinning as known, for example, from U.S. Pat. No. 4,258,541, granted Mar. 31, 1981, contains a bent-off tube in which a wire is pressed against the internal surface of the tube. The wire has a plurality of turns for the purpose of temporarily increasing the twist level or twist in the thread. The provision of the multi-turn wire requires that the wire is manufactured from an elastic metal. A ceramic material, for example, can not be provided at such location.
It is known that the yarn or the like formed during an open-end spinning operation has lower hairiness and possesses a harder or firmer handle than a yarn which is produced by a ring spinning operation. While these properties are desirable for many purposes, they are particularly undesirable for the manufacture of knitted goods, i.e. knitted fabrics.
Therefore, attempts have been made to further develop the open-end spinning operation and open-end spinning equipment such that yarn or the like possessing a soft handle also can be produced. Since such yarns must be less strongly twisted, there exists the difficulty that in many cases, the yarns do not satisfy the demands imposed upon such yarns when employing an open-end spinning operation. This can result in substantial disadvantages such as insufficient yarn tensile strength and insufficient yarn evenness or uniformity, an excessive number of thick and thin places or neps at the yarn, or an intolerably high yarn or thread break rate.